138 Seward and Gowan .— The Maidenhair 
able alliance between the two genera. The genera Whittleseya 
and Trichophyllum have been compared with Ginkgo 1 ) but our 
knowledge of these fossils is too incomplete to admit of more 
than speculation of little or no scientific value. 
Baiera. This genus calls for a fuller notice as including 
several species of Palaeozoic and Mesozoic age, some of which 
are almost certainly near relatives of the Maidenhair tree. 
Baiera was first defined by Braun 2 , who applied the name to 
some Triassic leaves which agree with Ginkgo in shape, but 
differ in possessing a lamina with more numerous and narrower 
segments. Braun and Schenk 3 included Baiera among the 
Ferns, and it is not improbable that some of the species may 
be best compared with such recent Ferns as Actinopteris 
radiata , Link. (PI. X, Fig. 67), or with species of Schizaea , 
e. g. 5 . dichotoma , Sw. (PI. X, Fig. 60), S', elegans , Sw., and 
others. 
Valuable evidence as to the Gymnospermous nature of 
some types of the genus is afforded by examples of flowers 
and seeds described by Schenk 4 , Heer 5 , and other authors. 
Among Palaeozoic leaves referred to Baiera , we have Baiera 
virginiana , Font, and Wh. 6 , from the Permian of Virginia, 
B. Raymondi , Ren. 7 , from Charmoy, and some other species. 
The genus was probably most widely spread during the 
Jurassic period, but there is fairly strong evidence in favour 
of extending its range to the Palaeozoic epoch. In con¬ 
sidering the range of Baiera it is important to bear in mind 
the absence of any well-marked distinguishing features between 
some species of this genus and some of the more dissected, 
forms of Ginkgo leaves. Among Jurassic leaves of the Ginkgo 
type [e. g. G. digitata (Brongn.) and G. Phillipsi , Nath.] it is 
easy to select a series illustrating a gradual transition from 
leaves with an entire lamina to those with a dissected lamina 
and linear segments, conforming in all respects to Braun’s 
1 Lesquereux (’79), PL IV ; Saporta and Marion (’85), p. 144 , Fig. 73 c. 
2 Braun (’43), p. 20 . 3 Schenk (’67). 
4 Ibid. 5 Heer (76), p. 51 . 
6 Fontaine and White (’80), PI. XXXVII. 
7 Renault (’96), p. 138 , Fig. 51 . 
